Coincident pulse operated switching means



Dec. 5, 1967 K. POLASEK 3,356,909

COINCIDENT PULSE OPERATED SWITCHING MEANS Filed Dec. 29, 1964 INVENTOR. KHRL POL/955A HaMx/m flrroRA/Er:

United States Patent O COINCIDENT PULSE OPERATED SWITCHING MEANS Karl Polasek, Hagersten, Sweden, assignor to Telelt'onaktiebolaget L M Ericsson, Stockholm, Sweden, a corporation of Sweden Filed Dec. 29, 1964, Ser. No. 421,960

Claims priority, application Sweden, Feb. 18, 1964,

1,941/64 4 Claims. (Cl. 317-137) ABSTRACT OF THE DISCLOSURE A switching device comprising at least two reed switches, a permanent magnet and a yoke of magnetic material arranged in a closed serial magnetic circuit having low reluctance when the switches are closed. Disposed about each reed switch is a separate winding which controls the operation of the associated switch. Each winding is separately energizable by its own source of current pulses. Both switches close and remain closed only when pulses are coincidentally received by both windings.

This invention pertains to switching devices operating electromechanically by means of coincidence current impulses. The switching devices include contacts having contact springs which conduct the energizing magnetic flux. Such contacts consist of two contact arms of magnetic material. At least one of the arms is pliable or resiliently suspended to obtain an electric contact that may be closed and opened by a magnetic field.

Particularly in telephone exchanges are such contacts found in pairs or in sets of several contacts which are to be actuated simultaneously, for example upon connection of two-wire or four-wire lines through selecting means. After the contacts have been actuated they are to be maintained in a closed condition without energy consumption so that they may be controlled by short current impulses. The arrangement according to the invention comprises at least two such contacts and at least one permanent magnet. There is a magnet winding for each contact. A magnetic circuit is obtained containing the permanent magnet and the contacts connected in series with each other. The magnetic circuit has only a small non-magnetic gap when all the contacts are closed. The switch is operated by means of electric circuits containing the magnet windings and one impulse generator so co-operating that a current impulse from an impulse generator, passing with a certain current direction through one of the windings closes the contact corresponding to the winding and that the permanent magnet holds the contacts in closed condition when all the contacts are closed and no current flows through the windings. However, none of the contacts holds when one or more of the contacts are opened, so that a comparatively large non-magnetic gap is included in the magnetic circuit. In addition, all the contacts are closed and then remain closed when current impulses with said current direction appear simultaneously in all windings, after which all the contacts will be opened when one or some of the contacts are caused to open.

The invention will be described more closely herebelow with reference to the accompanying drawings.

FIG. 1 shows the application of the invention for connecting a two-wire line, FIG. 2 for connecting a four-wire line with coincidence between two current impulses and FIG. 3 shows a six-wire connection for coincidence between three current impulses.

FIG. 4 shows the principle of a two-pole contact point of a crossbar switch designed according to the invention.

In FIG. 1, R1 and R2 are reed switches or contacts 3,356,909 Patented Dec. 5, 1967 "ice designed as protective tube contacts with resilient magnetic contact reeds included in a gas-filled envelope of glass. Between the two upper contact reeds there is provided a permanent magnet M and between the two lower contact reeds a yoke K of magnetic material. On the outside of the glass envelopes of the contacts R1 and R2, windings L1 and L2 are provided, one for each contact. Furthermore two pulse generators P1 and P2 are shown which send current impulses with different current directions at points of time determined by particular circuit arrangements that are not treated more in detail here, for example, a marker in an automatic telephone exchange. The magnet M and the yoke K are electrically insulated from the contact reeds in the contacts R1 and R2. The magnet M cannot alone operate any of the contacts R1 and R2. A current pulse from the impulse generator P1, having such a current direction in the winding L1 that a magnetic field co-operating with the magnetic field from the permanent magnet M is produced in the gap between the contact reeds of the contact R1, will operate the contact R1. A similar current pulse from the impulse generator P2, passing through the winding L2 operates the contact R2. The magnet M cannot retain the contact reeds in any of the contacts R1 and R2 as long as only one of the contacts is closed. If an impulse from pulse generator P1 arrives simultaneously with an impulse from pulse generator P2, both contacts R1 and R2 will be closed. A magnetic circuit is thereby closed through the magnet M, contact R1, yoke K and contact R2. In this circuit the contacts R1 and R2 are maintained in closed condition even when no current flows through the two windings L1 and L2. A current impulse passing through either or both windings L1 and L2 respectively with inverse current direction relatively to the operating impulse, extinguishes the magnetic field in the above mentioned magnetic circuit, whereby both contacts will open.

The yoke K may be replaced by a permanent magnet which co-operates with the magnet M. The magnets may consist of electrically non-conducting material.

In FIG. 2 are shown four reed contacts R1 and R4 each provided with a winding L1L4 and three permanent magnets MIL-M3. By means of a yoke K there is formed a magnetic circuit containing all contacts and magnetis connected in series with each other. Two electric circuits, each of which contains tWo of the windings and one impulse generator P1 and P2, respectively, are used to control the contacts. A current impulse which co-operates with the magnets Ml-MS, passing through one of the electric circuits operates only those contacts, for example contacts R1 and R3, the windings L1 and L3 of which are included in the circuit. The magnets M1-M3 cannot maintain the contacts R1 and R3 in operative condition if the contacts R2 and R4 are opened. It current impulses appear simultaneously in both circuits, all the contacts Ric-R4 will be closed and are then held by the magnetic circuit passing through the yoke K and the magnets M1- M3 even when no current flows through the windings L1L4. A current impulse passing with inverse current direction through either of the two electric circuits causes all contacts R1-R4 to open.

FIG. 3 shows six contacts R1-R6 and six permanent magnets Ml-M6 arranged so as to form a magnetic circuit. Each contact has one winding. There are three electric circuits each containing two windings and one pulse generator P1-P3 which controls the contacts so that these are operated and released substantially at the same time. The magnets M1-M6 cannot operate the contacts R1-R6 but only hold them in closed condition when all contacts are closed. Only when a current impulse appears simultaneously in the three electric circuits will all the contacts Rl-Ro be closed simultaneously. A current impulse with inverse current direction in one of the circuits brings about that all contacts open.

The contacts R1R6 may be connected in different ways. The contacts R1, R3 and R5 may for example be connected in series to the one branch of a two-wire line and R2, R4, R6 are connected in series to the other branch of the line. Thus none of the line branches is connected through the contact means without also the other being through-connected simultaneously.

FIG. 4 shows how a two-pole contact point of a crossbar switch may be designed according to the invention. The talking wires a and b of a selector are to be connected through the contact point to a line a1, b1. The contact point is composed of two contacts R1, R2 having each a winding L1, L2 and two permanent magnets M1, M2 made of electrically non-conducting material, and a rectifier B. Common to a large number of contact points there are provided two interruptors P1 and P2 and a direct current battery B. The interrupter P1 connects the negative pole of the battery to a conductor II which corresponds to the line a1, b1 and the interruptor P2 connects the positive pole of the battery to the conductor t2 which corresponds to the wires a, b of the selector. When the conductors t1 and 22 are simultaneously connected to the battery B, a current impulse will be obtained through the windings L1 and L2 and the contacts R1 and R2 are closed. After the termination of the impulse both contacts are held in closed condition by the magnets M1 and M2. For the interruption of the connection there is provided an auxiliary winding L3 which encloses both contacts R1 and R2. A current impulse from a disconnecting means P0 through the winding L3 brings about that, independently of the current direction, both contacts R1 and R2 will open. A plurality of windings L3 belonging to dilferent contact points in the selector, may be connected in series and receive current simultaneously from P0.

I claim:

1. Electromagnetically operated switching means comprising at least two contact sets, each of said contact sets including two .contact springs of magnetically conductible material, at least one permanent magnet, means for maintaining said contact sets and said permanent magnet in a series magnetic circuit which has an inconsiderable nonmagnetic gap when the contact springs of each contact set are in contact, a first winding means inductively coupled to one of said contact sets, a second winding means inductively coupled to the other of said contact sets, a first source of current pulses connected to said first winding means, and a second source of current pulses connected to said second winding means, said winding means being phased with respect to each other and said permanent magnet having a strength such that current pulses received by said Winding means coincidently from their associated current pulse sources cause each of said contact sets to close and remain closed after the occurrence of said current pulses and all of said contact sets opening when at least one of said contact sets is opened.

2. An electromagnetically operated switching means comprising first and second reed switches and permanent magnet means, said reed switches and said permanent magnet means being arranged in a series magnet circuit which has an inconsiderable non-magnetic gap when said reed switches are closed, a first operating winding inductively coupled to said first reed switch, a second operating winding inductively coupled to said second reed switch, first and second interrupters, each having first and second terminals, a diode, means for connecting said operating windings and said diode in series between the second terminals of said interrupters, and a direct current source serially connecting the first terminals of said interrupters, said operating windings being so phased and the strength of said permanent magnet means being such that said reed switches close when said interrupters close simultaneously and remain closed when either one of said interrupters thereafter opens.

3. The switching means of claim 2 further comprising means for opening at least one of said reed switches.

4. The switching means of claim 2 further comprising a further winding means inductively coupled to at least one of said reed switches and a current pulse source connected to said further Winding means so that a current pulse through said further winding means causes both of said reed switches to open.

References Cited UNITED STATES PATENTS 3,029,369 4/1962 Lang et al. 3l7150 3,042,900 7/1962 Werts 335151 X 3,215,795 9/1965 Matthias 335-153 3,253,097 5/1966 Wagar 335-153 3,273,088 9/1966 Grobe et al 335153 OTHER REFERENCES IBM Technical Disclosure Bulletin, vol. 5, No. 7, December 1962, Reed Switch Logic Elements, by T. G. Leary.

MILTON O. HIRSHFIELD, Primary Examiner.

I. A. SILVERMAN, Assistant Examiner. 

1. ELECTROMAGNETICALLY OPERATED SWITCHING MEANS COMPRISING AT LEAST TWO CONTACT SETS, EACH OF SAID CONTACT SETS INCLUDING TWO CONTACT SPRINGS OF MAGNETICALLY CONDUCTIBLE MATERIAL, AT LEAST ONE PERMANENT MAGNET, MEANS FOR MAINTAINING SAID CONTACT SETS AND SAID PERMANENT MAGNET IN A SERIES MAGNETIC CIRCUIT WHICH HAS AN INCONSIDERABLE NONMAGNETIC GAP WHEN THE CONTACT SPRINGS OF EACH CONTACT SET ARE IN CONTACT, A FIRST WINDING MEANS INDUCTIVELY COUPLED TO ONE OF SAID CONTACT SETS, A SECOND WINDING MEANS INDUCTIVELY COUPLED TO THE OTHER END OF SAID CONTACT SETS, A FIRST SOURCE OF CURRENT PULSES CONNECTED TO SAID FIRST WINDING MEANS, AND A SECOND SOURCE OF CURRENT PULSES CON- 